Pneumatic sewage ejector



Jan 21, 1964 E. J. cxABAT-rARl' ETAL 3,118,391

PNEUMATIC sEwAGE EJEcToR Filed Oct. 12, 1959 2 Sheets-Sheet 1 /q 4ri 5 @VEA/Uff United States Patent O 3,118,391 PNEUMATKC SEWAGE EJECTOR Emil l'. Ciahattari, Chicago, and Eugene A. Bishop, lr.,

Evanston, lll., assignors to Ycornans Brothers Company, Melrose Parli, lll., a corporation of Belaware Filed Oct. 12, 1959, Ser. No. 8%,692 4 Claims. (Cl. 11B-240) The present invention relates generally to pneumatic sewage cjectors and in particular to an improved liquid level control in such a sewage ejector.

Generally, in previously available pneumatic sewage ejectors, a two-electrode liquid level control has been used. One of the electrodes, which is longer than the other, is extended into the receiver of the pneumatic ejector to the position of the desired low level of the sewage in the receiver, and the othe-r electrode is erendcd into the receiver to the position of the desired high level of the sewage. ln operation, when the sewage level inthe receiver reaches .the lower end of the shorter electrode, ya circuit is completed from the receiver, which is grounded, through the sewage and to the shorter electrode. Upon the completion of the circuit, pressure air is delivered to the receiver, which lair causes the sewage to be ejected from the receiver until the grounded sewage breaks contact with the lower end of the longer electrode.

While such a level control has provided an elicctive level control in a sewage ejector, certain diiliculties have been experienced in its operation. For example, when a rag or other conductive debris lin the sewage clings to the longer electrode, it prevents the sewage from breaking lcontact with the longer electrode. Consequently, pressure air is `continually supplied to the receiver, -thereby `preventing sewage in the inlet pipe from collecting in the receiver. When the debris is an insulator, the sewage is prevented trom making contact with the electrode and, accordingly, the ejector becomes inoperative.

Another diiculty that has occurred with the previously available liquid level control is that grease from the sewage collects in the receiver and bridges the gap between the longer electrode and the shorter electrode. When the grease is conductive, pressure air is delivered to the receiver as soon as the sewage level contacts the longer electrode. Since the introduction of pressure `air is discontinued when the sewage level drops below the longer electrode, the bridging of the electrodes results in a rapid on-otl operation and the sewage is thus prevented from collecting in the receiver. When the grease is non-conductive, the sewage is prevented from contacting the longer electrode and the ejector becomes inoperalive.

An object of the present invention is the provision or' an improved liquid level control in a sewage ejector. Another object of the invention is the provision of a relatively trouble-free, electrically operated liquid level control in a sewage ejector. A further object is the provision of' a relatively inexpensive liquid level control of the type indicated which is readily adaptable to existing sewage ejectors.

@the-r objects and advantages of the present invention will become apparent by reference to the following description and accompanying drawings.

ln the drawings:

FGURE l is a schematic view of a sewage ejector showing various features of the present invention; and

FlGURE 2 is a schematic view of another embodiment of the sewage ejector.

The sewage ejector, in accordance with the present invention, includes a receiver for sewage having a sewage inlet pipe and `a sewage outlet pipe. A source ott pressure air is connected through an air inlet pipe to the Cil 3,ll8,39l Patented Jan. 2l, 1964 ice receiver, which air inlet pipe is provided with a valve means. Means are connected to the valve means so as to actuate the valve means ier a preselected time interval when lthe sewage in the receiver reaches a predetermined level. The actuating rneans includes an electrode extending into @the receiver to the predetermined level, and means for grounding the sewage in the receiver. The actuating means also includes a switch means connected to the grounding means and the electrode for actuating the valve means when the grounded sewage contacts the electrode. The switch means also operates a timing means which keeps the valve means open for introduction of pressure air into the ejector throughout the preselected tinie interval.

More particularly, the sewage ejector shown in FIG- URE l is a combination pneumatic ejector and aerator and includes a receiver lo having a generally cylindrical body portion and ya dome-shaped upper portion. A removable central cover plate llZ is provided on the upper portion to provide access to the receiver.

Sewage is delivered through inlet piping 14 to a fluid inlet passageway `lo at the lower portion of the receiver lll. The sewage is collected in the receiver 10 until the sewage level rnalres Contact with an electrode l extending vertically through the dome of the receiver lil. When the sewage level contacts the electrode 18, a liquid level control, which is described more fully hereinafter, is actuated, whereby pressure -air is delivered to the receiver lil' for a predetermined time interval to eject the sewage 'from the receiver lil.

Pressure air is delivered through an air inlet pipe 20 extending vertically through the dome to an annular conduit 22 disposed in the lower portion of the receiver 10. The annular conduit 2?. is provided with small open-ings to allow pressure air to enter the receiver. Air is thus diffused at the lower portion of the sewage within the receiver lil, then bubbles up upwardly through the sewage and is collected within the dome of the receiver l0.

A portion of the pressure air which is collected in the dome of the receiver lil is permitted to bleed oil to the atmosphere through a restricted oritlce litting 26 at the upper end of an air exhaust pipe 28 which is attached to the cover plate l2 of the receiver lt). With this arrangement, the sewage in the receiver lil is subjected to a greater quantity of air during the ejection cycle and the air is dispersed through the sewage in the form of very small bubbles. As the pressure of the air in the receiver lll increases, it forces the highly aerated sewage within the receiver l0 out through a iluid outlet passageway El) in the lower portion o the receiver' lil to outlet piping 32 which carries the sewage to subsequent treatment apparatus. Check valves 34 and 35 are disposed respectively in the inlet piping lli and the outlet piping 32 to prevent back ow of the sewage.

As shown in FGURE l, pressure air is delivered to the air inlet pipe 2li through a piping arrangement which is adapted to deliver pressure air to the receiver 1t) and to vent the receiver itl after ejection of the sewage to permit the receiver lll to again lill to the predetermined upper level. The piping arrangement includes a two-position, three-way diaphragm valve 36 which is connected by a delivery pipe 2d to the air inlet pipe Ztl. Valve 3o is normally disposed to place the exhaust pipe 23 in communication with the atmosphere through the pipe 39. When the diaphragm valve 36 is actuated, as will be described hereinafter, the exhaust pipe 39 is closed and pressure air is fed from a source of pressure air, such as a compressor (not shown) through the delivery pipe 3S to the air inlet pipe 2d and thence into the receiver lll. A check valve fill is disposed in the delivery pipe 3a to prevent back iiow of sewage through the annular conduit 22.

When the diaphragm valve is in its cle-energized position, air in the receiver iti is permitted to vent to the atmosphere through the exhaust 28, through a connecting pipe d2 connected between the delivery pipe 38 and the air exhaust pipe 23, and thence through the diaphragm valve 3o to the vent pipe fr?. A one-way check valve in is disposed in the connecting pipe l2 to prevent pressure air from being introduced into the receiver ltl above the sewage during the ejecting cycle, the valve 46 being held closed by the pressure air in the delivery pipe As shown in FGURE l, the diaphragm valve 36 is actuated by pressure air supplied to the diaphragm of the valve 36 through a tubing d8 connected upstream of the valve 3d. A solenoid valve Sil is connected into the tubing 43 to control the supply of pressure air and thus the actuation of the diaphragm valve 35.

As previously indicated, when the sewage level in the receiver l@ contacts the electrode lid, a liquid level control is actuated. The control is actuated by the sewage completing the circuit between the electrode Till and the receiver l@ which is suitably grounded. Of course, the sewage may be grounded by extending a second electrode into the receiver, which electrode extends substantially to the bottom of the receiver. It should be realized that the second electrode in the arrangement is utilized to ground the sewage, which is quite dilerent from the previously available liquid level controls where the second electrode controls the lower lei-el of the sewage in the receiver.

As shown in FIGURE l, the level control includes a transistor switching circuit 52 connected to the electrode 1S and the ground connection. A transistor switching circuit S2 is utilized so that a minor current through the sewage controls a control relay Sd. Higher current in the sewage may cause electrolysis.

The transistor' switching circuit 52 includes a p-n-p transistor 56, the base 5S of which is connected to the electrode 18. The emitter d@ of the transistor 56 is connected to the positive side of a direct current power source 62 which, as shown in the drawings, is a full-wave bridge rectier circuit. The collector ed of the transistor 56 is connected through the coil of the control relay 54 to the negative side of the power source @2.

The base 5S of the transistor 56 is biased by a resistor 68 connected between the grounded receiver lil and the negative side of the power source d2. The resistor d3 is made of a resistance small enough so that when a circuit is completed between the receiver ld and the electrode 18, su'liicient current passes through the collector 6d of the transistor Se to energize the control relay 5d. Of course, the resistor et; is not made too small or else the transistor 5d may be damaged.

Alternating voltage is ted to the bridge rectifier circuit 62 by an isolating transformer 7d, which is connected to a lill-volt line through an automatic contact '72 of a hand-olii automatic switch 74.

When the relay 5d is energized, a normally open relay contact 76 associated therewith is closed. The contact i6 is connected in series with thc automatic Contact i2 and the coil of an auxiliary relay A normally open Contact Sti actuated by the auxiliary relay 7S is connected in series with the solenoid 5@ that controls the diaphragm valve 36. Accordingly, when the contact Si? of the auxiliary relay 78 closes, pressure air is delivered to the receiver itl.

Since the circuit between the electrode .TLS and the grounded receiver fr@ is broken when the sewage level drops, a holding-timing circuit is provided to keep the solenoid Si) energized for a preselected time interval.

ln the embodiment shown in FIGURE 1, the solenoid Sli is kept in an energized position by providing a circuit which connects the electrode l to ground for a preselected time interval after the sewage contacts the electrode 18. The electrode 18 is connected to ground through a Cil i normally open contact Si. of a timing relay Sii, and an automatic Contact `35 of a hand-oilp automatic switch SS, -which is ganged with the previously mentioned hand-off automatic switch '74.

The coil of the timing relay S4 is connected in series 'with the collector- @d of an n-pn transistor 92 connected as a switch. Positive voltage is provided for the collector .9@ by connecting the positive terminal of the power source 62 through a load Vresistor 9d and the coil of the timing relay 8dto the collector 9h. The emitter 96 of the transistor h2 is connected directly to the negative terminal of the power source `62.

The transistor 92 is switched 'from a conducting con dition, wherein sufcient collector current flows to operate the timing relay 8d, to a cut-oti condition, wherein the collector current is insulicient to actuate the timing relay 84, by a resistance-capacitance timing circuit connected between the base 98 and emitter gd of the transistor 92. The timing circuit includes a condenser lili? which is charged to a predetermined voltage by connecting the condenser through a normally closed contact 162 of the auxiliary relay 78 to a voltage divider lille. The voltage divider lili/' includes a pair of series resistors like and M33 connected across the power source 62, the voltage to which the condenser lith is charged depending upon the ratio of the resistors lilo and '108 and the voltage of the power source 62.

When the auxiliary relay 78 is energized, the condenser lill) is connected through a normally open contact lill of the auxiliary relay 78 to the base 9S of the transistor 92. A biasing resistor lilZ is inserted in series between the condenser lltit and the base 98 to prevent excess collector current from initially owing through the transistor @Z and damaging the same.

The discharge current from the condenser 100 is partially shunted by an adjustable resistance 114 connected in parallel with the biasing resistance ll?, and the baseemitter internal resistance of the transistor 92. The adjustable resistance 114, which includes a rheostat 116 and a low limit resistor MS, may be varied to change the discharge time of the condenser Miti and thus the length of time that the solenoid Sli is energized.

lf the source of pressure air is a compressor, the starter coil of the compressor starter may be connected in parallel with the solenoid 5l) so as to only operate the compressor when pressure air is required.

The hand contact 119 of the handoff-automatic switch 83 is connected so as to by-pass the timing relay contact 82, and thus connect the electrode 18 to ground, in order that pressure air may be delivered to the receiver lli as desired.

In operation, the sewage enters the receiver lll and fills the receiver 1d until it reaches the lower end of the electrode 11S. When the sewage reaches the lower end of the electrode a circuit is completed between the grounded receiver il@ and the electrode 18, thus permitting a current to ilow in the base circuit of the transistor 56.- This current in the base circuit of the transistor 56 causes a much higher current to llow through the collector circuit of the transistor S6, which current is sulicient to energize the control relay 54 and close the control relay contact 75. When the control relay Contact closes, a circuit is completed to the auxiliary relay 78, thereby closing the auxiliary relay contact 80 and energizing the solenoid 50. The 4auxiliary relay 78 being energized causes the auxiliary relay contact .W2 to open and auxiliary relay contact lltl to close, thereby connecting the charged condenser lil@ into the base circuit of the transistor 92. Current llowing in the base circuit causes col-lector current to flow, thus actuating the timing relay 84 and closing the timing relay contact 82, thereby completing the circuit between the electrode 18 and ground.

When the solenoid Sli` is energized, pressure air is delivered to the diaphragm valve 36 which then moves to close oil vent 39 and place the source of pressure air in.

communication with pipe 38 for delivery of pressure air to the receiver 1t), thereby ejecting the sewage therein. Pressure air is delivered until the condenser 10d is surticiently discharged to de-energize the timing relay 84 and thus open the circuit between the electrode -18v and ground. The yopening of the -circuit allows the solenoid 50 to close and, if -a compressor is used, allows the compressor to be deactivated.

FIGURE 2 shows a more expensive embodiment of the level control, wherein an electrical timer is utilized to control the time interval of delivery of pressure air. Substantially similar parts to those shown in 'FIGUR-E l are indicated by the same reference numerals, with the subscript 11.

As shown in FlGURE 2, the isolating transformer 70a is connected through an automatic contact 120 of a handoff-automatic switch 1.21. When the relay 54a is energized by the sewage completing a circuit between the electrode l-Sa and ground, a normally open relay contact Et22 associated therewith is closed. The contact 122 is connected in series with the automatic contact 120 and the solenoid Stia that controls the diaphragm valve 36a. Accordingly, when the contact 122 of the control relay 54a closes, pressure air is delivered to the receiver lila.

Since the circuit between the electrode 18a and the grounded receiver lila is broken when the sewage level drops, a holding-timing circuit is provided to keep the solenoid Sua energized for a preselected time interval. The holding-timing circuit includes a timer 124, the coil or motor of which is connected in parallel with the solenoid de and an auxiliary relay 126, the coil of which is connected in parallel with the solenoid 50a. Accordingly, when the solenoid 50a is energized, the timer 124 and auxiliary relay l26 are also energized.

The timer 124 is provided with a normally closed contact 12S, and the auxiliary relay 126 is provided with a normally open contact i3d, which contacts are connected in series, and the series contacts, in turn, are connected in parallel with the control relay contact 122. Accordingly, the auxiliary relay contact 13@ and the timer contact t28 by-pass the control relay contact 22 and maintain the solenoid Stia in an energized position until the timer contact 12S opens a preselected time interval after the operation of the timer 124 is initiated.

lt the source of pressure air is a compressor, the starter coil of the compressor starter may be connected in parallel with the solenoid Stia so as to only operate the cornpressor when pressure air is required.

The hand contact l32 of the hand-ott automatic switch lill is connected so as to by-pass the control relay contact 122, in order that pressure air may be delivered to the receiver lltla as desired.

In operation, the sewage enters the receiver lila and fills the receiver lila until it reaches the lower end of the electrode 551. When the sewage reaches the lower end ot the electrode ld, a circuit is completed between the grounded receiver lila and the electrode 38a, thus permitting a current to flow in the base circuit of the transistor 56a. This current in the base circuit of the transistor 56a causes a much higher current to ilow through the collector circuit of the transistor 56a, which current is suiiicient to energize the control relay 54a and close the control relay contact 122. When the control relay contact 122 closes, a circuit is completed to the auxiliary relay 1r26, the timer 124, and the solenoid 5tlg. When the solenoid 5tlg. opens, pressure air is delivered to the diaphragm valve 36a which then moves to close oit vent 39a and place the source of pressure air in communication with pipe 38a for delivery of pressure air to the receiver a, thereby ejecting the sewage therein. Pressure air is delivered until the timer contact 128 opens and de-energizes the solenoid Sila and shuts oit the compressor, if a compressor is used.

lt should be realized that the liquid level control may be used with different ejection arrangements than that described above. For example, the liquid level control may be used with the ejector shown and described in United States patent, No. 2,300,039. Moreover, the liquid level control may be utilized to control diaphragm valves which, in some applications, are substituted lor the check valves in the inlet and outlet piping.

From the above it can be `seen that since the electrode in the receiver remains substantially out of the sewage at all times, it cannot become fouled with debris or grease contained in sewage. Consequently, the liquid level control is less likely to become inoperative.

Various changes and modiiications may be made in the above described ejector without deviating from the spirit or scope of the present invention. Various of the features ot the invention are set forth in the accompanying claims.

W e claim:

l. A pneumatic sewage ejector comprising a receiver for sewage, a sewage inlet pipe connected to said receiver, a sewage outlet pipe 'connected to the lower portion of said receiver, an air inlet pipe connected to said receiver, a source of pressure air connected to said air inlet pipe, valve means in said air inlet pipe, and control means for opening said valve means when the sewage in said receiver reaches a predetermined level tol provide the ow of pressure air into said air inlet pipe, said control means including an electrode extending into said receiver to said predetermined level, means grounding said sewage within said receiver, a relay having a normally open contact, switch means connected to said grounding means and said electrode for actuating said relay when the grounded sewage contacts said electrode, a power source, an electrical actuating means for said valve means, said valve actuating means, power source and contact being connected in series whereby when said contact closes said valve means is opened to introduce pressure air into said air inlet pipe, an electrically operated timing means connected in parallel with said valve actuating means, said timing means having a normally closed contact, an auxiliary relay connected in parallel with said timing means, said auxiliary relay having a normally open contact, said auxiliary relay Contact and said timer contact being connected in series, the series contacts being connected in parallel with said relay contact.

2. A pneumatic sewage ejector comprising a receiver for sewage, a sewage inlet pipe connected to said receiver, a sewage outlet pipe connected to the lower portion of said receiver, an air inlet pipe connected to said receiver, a source of pressure air connected to said air inlet pipe, valve means in said air inlet pipe, and control means for actuating said valve means for a preselected time interval when the sewage in said receiver reaches a predetermined level to provide the ilow of pressure air into said air inlet pipe, said control means including an electrode extending into said receiver to said predetermined level, means grounding said sewage within said receiver, a relay having a normally open contact, switch means connected to said grounding means and said electrode for actuating said relay when the grounded sewage contacts said electrode, an auxiliary relay having a normally open Contact, a power source, said power source, said auxiliary relay and said relay contact being connected in series, an electrical actuating means, said electrical actuating means, said power' source and said auxiliary relay contact being connected in series whereby when said auxiliary relay contact closes said valve means is opened to introduce pressure air into said air inlet pipe, and means operated by said auxiliary relay contact for short circuiting said electrode to ground for said preselected time interval whereby said valve actuating means is energized for said preselected time interval.

3. A pneumatic sewage ejector comprising a receiver for sewage, a sewage inlet pipe connected to said receiver, a sewage outlet pipe connected to the lower portion ot said receiver, an air inlet pipe connected to said receiver, a source of pressure air connected to sair air inlet pipe, valve means in said air inlet pipe, and control means for actuating said vaive means for a preselected time interval when the sewage in said receiver reaches a. predetermined level to provide the iiow of pressure air into said air inlet pipe, said actuating means including an electrode extending into said receiver to said predetermined level, means grounding said sewage Within said receiver, a relay coil having a normally open Contact, a transistor switch circuit connected to said relay and said grounding means and said electrode in such a Way that a complete circuit between said grounding means and said electrode energizes said relay, said contact being connected so as to actuate the valve means when said contact closes, and a resistance-capacitance timing circuit operated by said Contact for short circuiting said electrode to ground for the preselected time interval whereby said valve means is kept open for the introduction of pressure air into said air inlet pipe for said preselected time interval.

4. A pneumatic sewage eiector comprising a receiver for sewage, a sewage inlet pipe connected to said receiver, a sewage outlet pipe connected to the lower portion of said receiver, an air inlet pipe connected to said receiver, a source of pressure air connected to said air inlet pipe, valve means in said air inlet pipe, and control means for opening said valve means when the sewage in said receiver reaches a predetermined level to provide the ilow of pressure air into said air inlet pipe, said control means including an electrode extending into said receiver to said predetermined level, eans grounding said sewage within said receiver, a control relay having a normally open contact, switch means connected to said grounding means and said electrode for actuating said relay when the grounded sewage contacts said electrode, -a. power source, an auxiliary relay having two normally Open contacts and a normally closed Contact, said power source, said auxiliary relay and said control relay contact being connected in series, an electrical actuating means for said valve means, said va'ive actuating means, power source and one of said auxiliary relay normally open contacts being connected in series whereby when said auxiiiary relay Contact closes said valve means is opened to introduce pressure air into said air inlet pipe, a condenser, said condenser bein,f7 connected through said anxiliary relay normally closed contact to a portion of said power source, a timing relay having a normally open contact which is connected between the electrode and ground, a transistor connected as a switch with the timing relay as a load, the other of said auxiliary relay normally open Contact connecting said condenser so as to actuate said transistor switch when said auxiliary relay is energized.

References Cited in the le of this patent UNITED STATES PATENTS 1,826,477 Clpp Get. 6, 1931 1,843,686 Koch Feb. 2, 1932 2,300,039 Yeomans Cct. 27, 1942 2,316,494 Tipton Apr. 13, 1943 2,326,442 De Wi Aug. 10, 1943 2,434,027 Whittington lan. 6, 1948 2,456,456 Smith Dec. 14, 1948 2,550,093 1951 2,634,682 1953 2,669,941 Stafford Feb. 23, 1954 2,892,414 Griffith `iune 30, 1959 2,947,931 Hubby Aug, 2, 1960 3,019,764 Schilling Feb. 6, 1962 FOREGN PATENTS 599,357 Germany June 29, 1934 

1. A PNEUMATIC SEWAGE EJECTOR COMPRISING A RECEIVER FOR SEWAGE, A SEWAGE INLET PIPE CONNECTED TO SAID RECEIVER, A SEWAGE OUTLET PIPE CONNECTED TO THE LOWER PORTION OF SAID RECEIVER, AN AIR INLET PIPE CONNECTED TO SAID RECEIVER, A SOURCE OF PRESSURE AIR CONNECTED TO SAID AIR INLET PIPE, VALVE MEANS IN SAID AIR INLET PIPE, AND CONTROL MEANS FOR OPENING SAID VALVE MEANS WHEN THE SEWAGE IN SAID RECEIVER REACHES A PREDETERMINED LEVEL TO PROVIDE THE FLOW OF PRESSURE AIR INTO SAID AIR INLET PIPE, SAID CONTROL MEANS INCLUDING AN ELECTRODE EXTENDING INTO SAID RECEIVER TO SAID PREDETERMINED LEVEL, MEANS GROUNDING SAID SEWAGE WITHIN SAID RECEIVER, A RELAY HAVING A NORMALLY OPEN CONTACT, SWITCH MEANS CONNECTED TO SAID GROUNDING MEANS AND SAID ELECTRODE FOR ACTUATING SAID RELAY WHEN THE GROUNDED SEWAGE CONTACTS SAID ELECTRODE, A POWER SOURCE, AN ELECTRICAL ACTUATING MEANS FOR SAID VALVE MEANS, SAID VALVE ACTUATING MEANS, POWER SOURCE AND CONTACT BEING CONNECTED IN SERIES WHEREBY WHEN SAID CONTACT CLOSES SAID VALVE MEANS IS OPENED TO INTRODUCE PRESSURE AIR INTO SAID AIR INLET PIPE, AN ELECTRICALLY OPERATED TIMING MEANS CONNECTED IN PARALLEL WITH SAID VALVE ACTUATING MEANS, SAID TIMING MEANS HAVING A NORMALLY CLOSED CONTACT, AN AUXILIARY RELAY CONNECTED IN PARALLEL WITH SAID TIMING MEANS, SAID AUXILIARY RELAY HAVING A NORMALLY OPEN CONTACT, SAID AUXILIARY RELAY CONTACT AND SAID TIMER CONTACT BEING CONNECTED IN SERIES, THE SERIES CONTACTS BEING CONNECTED IN PARALLEL WITH SAID RELAY CONTACT. 